/Engine/Plugins/Experimental/Mutable/Source/MutableRuntime/Public/MuR/Image.h
Calculate the size of the image data in bytes, regardless of what is allocated in m_data, only using the image descriptions. For non-block-compressed images, it returns 0.
static int32 CalculateDataSize ( int32 SizeX, int32 SizeY, int32 LodCount, [EImageFormat](API\Plugins\MutableRuntime\MuR\mu__EImageFormat) Format )